PALO ALTO, Calif. — A free online course at Stanford University on artificial intelligence, to be taught this fall by two leading experts from Silicon Valley, has attracted more than 58,000 students around the globe — nearly four times the size of Stanford’s entire student body.

The course is one of three being offered experimentally by the Stanford computer science department to extend technology knowledge and skills beyond this elite campus to the entire world, the university is expected to announce Tuesday.

The online students will not get Stanford grades or credit, but they will be ranked in comparison to the work of Stanford students and will receive a “statement of accomplishment.”

For the artificial intelligence course, students may need some higher math, like linear algebra and probability theory, but there are no restrictions to online participation. So far, the age range is from high school to retirees, and the course has attracted interest from more than 175 countries.

The instructors are Sebastian Thrun and Peter Norvig, two of the world’s best-known experts in artificial intelligence. In 2005 Thrun led a team of Stanford students and professors in building a robotic car that won a Pentagon-sponsored challenge by driving 132 miles over unpaved roads in a California desert. More recently he has led a secret Google project to develop autonomous vehicles that have driven more than 100,000 miles on California public roads.

Norvig is a former NASA scientist who is now Google’s director of research and the author of a leading textbook on artificial intelligence.

The computer scientists said they were uncertain about why the artificial intelligence, or AI, class had drawn such a large audience. Thrun said he had tried to advertise the course this summer by distributing notices at an academic conference in Spain but had gotten only 80 registrants.

Then, several weeks ago he emailed an announcement to Carol Hamilton, the executive director of the Association for the Advancement of Artificial Intelligence. She forwarded the email widely, and the announcement spread virally.

The two scientists said they had been inspired by the recent work of Salman Khan, an MIT-educated electrical engineer who in 2006 established a nonprofit organization to provide video tutorials to students around the world on a variety of subjects via YouTube.

“The vision is: Change the world by bringing education to places that can’t be reached today,” Thrun said.

The three online courses, which will employ both streaming Internet video and interactive technologies for quizzes and grading, have in the past been taught to smaller groups of Stanford students in campus lecture halls. Last year, for example, Introduction to Artificial Intelligence drew 177 students.

The two additional courses will be an introductory course on database software, taught by the computer science department chair, Jennifer Widom, and an introduction to machine learning, taught by Andrew Ng.